The Pilot has a lot of heartwarming moments anyway, especially for someone rewatching it, but in particular there is an offhand remark from Tommy about how long it's been since he got laid. "By my rough estimate... 1,839 days". Tommy counted the days since his best friend went missing!
In "Damaged", Thea gives one statement that shows how much she truly loves her brother "I can't lose you again."
Oliver and Thea teasing their mother in "Legacies", mostly because of the fluid chemistry; it's a rare moment where they act like normal siblings without baggage.
Tommy gives Thea a ride home after a night of heavy drinking. Clearly ashamed of what she did, Thea begs Tommy not to hate her and Tommy replies he could never hate her.
At the end when Oliver and his mom share burgers at the Big Belly Burger joint (Moira even eats with her hands, despite her usual stuffiness). Despite the secrets he's keeping and some of her more questionable actions, they're still family and they still love each other.
The end of "Vendetta", when Tommy asks Oliver for a job, outright rejects taking any of his trust fund, and Ollie giving Tommy the job. It shows that they both care about the other much more than assumed, and Oliver is willing to help Tommy change, even if it means losing Laurel. Overall, their entire relationship can be considered this since, when first introduced, many assumed Tommy to be a shallow wingman of Oliver's.
Diggle caring enough to be someone for Ollie to confide in as well as a voice to temper Ollie's actions. But particularly giving Ollie props for taking the risk in opening up to Helena after previously chewing him out on that particular subject (and before that, pushing him to confide in more people).
Diggle: The Oliver I met a few months ago wouldn't have been able to do that.
"Year's End" has a small one in Ollie including Walter in his 'reason to hold the Queen Christmas party' speech. For Ollie, it's a nice gesture to show Walter that he considers him a part of the family. For Walter, it must be nice to hear Ollie say as such considering from Ollie's perspective, he came home to a different family.
The way Oliver acts about Thea in "Vertigo" is Big Brother Instinct at its finest. Particular mention goes to the scene where they walk to the court house and news reporters start swarming in on her. She holds her hand out to him and he takes it, then muscles his way past the mob while protecting her.
Felicity's statement to Ollie in the restaurant when she realizes the book Walter had is big news: "You've dropped some fairly ridiculous lies on me, and yet ... I still feel like I can trust you."
Also heartwarming, Oliver first responds with a flippant quip and Felicity's face and posture tense going "Yeah, lying. Again." Oliver immediately apologizes and answers her seriously. It's a nice little non-verbal moment cementing in the fact that, yes, Felicity is actually a fairly good judge of real Oliver Queen vs. fake Oliver Queen.
In "Dead to Rights", when MalcolmMerlyn realizes people are attacking, the first thing he does is look for his son. He treats Tommy like crap, takes glee in tearing him down, but at the end of the day, he loves Tommy, and was even willing to reveal he's the Dark Archer to him. In the end, the two have a heart to heart, and Malcolm explains a bit of his backstory.
When Moira, who hired the hit on Malcolm, sees Tommy in the crowd and realizes that, if Malcolm dies, Tommy loses his father, and her face drops. She hates Malcolm, but she's not cold blooded enough to want to cause Tommy, her son's best friend since childhood & the nicest guy in the show, any pain at all.
Oliver tells Tommy who he is. And while Tommy is in shock, he still covers for him when the police question him. In later episodes, after the two fall out, Tommy still covers for him, regardless of his personal feelings about him.
In "Unfinished Business", Shado is afraid that what her father, Yao Fei had to do on the island to survive turned him into a monster. Island!Ollie reassures her by saying that Yao Fei saved his life.
In "Savior", Felicity fails to track a growing threat. Oliver doesn't blame her and says, "Sometimes we lose." She goes on to tell him (after noticing Oliver's tendency towards isolation) that maybe it is better off being alone, because she wouldn't know how she'd talk about what'd happened to her that day if she had a significant other in her life. After she figures out what happened with her error and the threat is neutralized. Oliver revisits the conversation.
Oliver:(quietly) Psst; by the way, if you ever need to tell someone about your day...you can tell me.
"Home Invasion": After seeing how important it is to him that he finds the Vigilante, Thea tells Roy that she'll do what she can to help him find the guy.
Thea: Finding him means the world to you, and you mean the world to me, so I'm here to help.
Tommy consoling the young Taylor, who has just lost his parents, just like Tommy himself lost his mother when he was a kid, and telling him that he can see his parents every time he closes his eyes.
Roy's reason for trying to find the Hood summed up easily:
Roy: It feels like my life is connected to his.
"The Undertaking": The family reunion with a rescued Walter, including Walter calling Oliver "son".
In the same scene, Ollie and Walter introducing Felicity to Moira and Thea as their friend.
In "Sacrifice", Ollie's final speech to a not long for this world Tommy.
Diggle and Felicity refusing to abandon Oliver when he needs them, cementing that they are True Companions. In that same scene, the Hood and Quentin cementing their alliance, each saying that the city needs the other.
Back in Island Time, how does Oliver gain the focus to fire his first accurate shot from a bow? When Fyers is holding Shado hostage and he's the only person still standing and able to do anything.
The Season Two opener, "City of Heroes", ends with someone coming to rescue Oliver and Queen Consolidated from a hostile takeover, someone mentioned as family after Moira's role in the Undertaking left the family without any friends. At the end of the episode, this backer walks in and it turns out to be Walter — no matter what's happened, he still considers Oliver and the company to be very close to him.
Oliver calling Felicity a good friend. It's easy to see that means a lot to her.
Moira tells Thea that being arrested and sent to jail has "freed" her from the burden that she had to do in terms of being involved with the Undertaking.
All of "Identity", Felicity is not happy with becoming Oliver's personal assistant (so that it doesn't look so odd for the CEO to go down to IT all the time); she tells him upfront that she didn't graduate from MIT just to fetch him coffee. Every single time he asks her, it's no. But at the end, Oliver's been having a rough day, so she brings him a cup, stating just this one.
Furthermore, this happens right after Oliver apologizes to Dig for not being there for him; even with Dig's joking remark that "this is getting dangerously close to hug territory", it's sweet to see them back on the same page. He even offers Ollie a ride home, though the new CEO proves to have some work to do.
Oliver: I'll find my own way.
Diggle: You always do.
Roy and Thea getting back together at the end, with him promising to stop fighting bad guys. After all, the Arrow has given him another way to help.
This other way to help, by the way, is a mix of Oliver both slowly accepting Roy and making sure Thea is happy, as relationship problems are the last thing she needs after Moira's being imprisoned and facing a death sentence.
In "Broken Dolls", Lance is wondering at Felicity's prowess with the computers while infiltrating a lab with the Arrow. That gets a smile of pride out of Ollie (under the cover of the hood)
Quentin openly thanking the Arrow for saving him and Laurel at the end.
"I might not agree with your methods, but I do agree with the results."
In "Crucible", Ollie is willing to let Quentin and Laurel hate him if it means allowing Sara to get back to her family. Also, Oliver and Sara holding hands, meaning that she will confront them.
In the same episode, Roy saves Cindy/Sin after the Mayor's attack. Thea grows to accept Roy's Chronic Hero Syndrome better, and Sin warms up to him. Meanwhile, in the hospital, Sara risks exposing herself just to make sure her friend is safe.
Sebastian Blood's genuine thanks to Oliver for saving him in the Mayor's attack, attributing it to Oliver's strength as a person rather merely being instinct as Oliver insisted. Of course, it's undercut by the reveal that Brother Blood isn't as selfless as he first appears.
A subtle one spanning over several episodes so far: both the Arrow and Felicity insist on calling Lance "Detective" in spite of his demotion, showing their respect for the guy.
In "League of Assassins", Sara reuniting with her father.
Thea and Oliver convincing Moira that whatever she's hiding, they won't stop loving her.
Oliver and Diggle sharing a bottle of vodka, probably courtesy of Anatoli Knyazev, and Ollie starting to open up more to Dig about what happened during his five years away.
Oliver insisting on confronting the Assassin Al-Owal along with Sara, because Al-Owal "threatened somebody that he cares about", namely her.
"Keep Your Enemies Closer", after Diggle has admitted to needing to find Lyla, who was going after Deadshot:
Oliver: Felicity, I think it's time we visited our Queen Consolidated subsidiary in Moscow.
Diggle: Oliver, what are you doing?
Oliver: Just need to help a friend.
Diggle: I can't ask you to do that.
Oliver: You didn't.
Moira reconciling Roy and Thea near the end of the episode.
Shado refusing to leave Slade behind, instead staying in the plane to help him recover from his burns, with both telling the other they'd always protect ones they care about. Usually their interactions consist of snarky comments, attempts to out-badass the other, or Slade hitting on her, so its kinda nice seeing them act genuinely caring for the other.
"State vs. Queen" — honestly this episode was just full of the heartwarmth, despite its actual plot line.
Moira is acquitted, against all odds. Sadly, this is marred when it's revealed Malcolm bribed the jury to get the verdict.
When Diggle appears to be sick, Oliver sends him home despite the fact that Oliver was going to need support as its the start of his mother's trials. When he collapses, Oliver rushes to him straight away, even though his mother's trial was still on-going for the day.
After it's revealed that Diggle's suffering a form of Vertigo withdrawal and Felicity reveals that The Count escaped the same way the Dollmaker did and the prison covered it up, Oliver looks furious and rather decisively and a little viciously grabs an arrow from his stash. Felicity starts to say "I know what you're thinking..." implying she thinks Oliver believes he should have killed the Count. Oliver replies quickly "No, you don't. I made a choice not to put an arrow in this guy... And it was the right choice.There's no more killing." Not only was it the explanation, but how he said it. He both lowered volume and calmed his voice to calm and bolster Felicity. And the arrow he grabbed? A possible cure for Diggle.
After that, Felicity gets kidnapped by the Count and Oliver immediately rushes off to save her despite the fact that he and Thea are waiting on his mother's verdict. The True Companionship between the three has grown stronger than ever, to the point that Oliver broke his promise to never kill again when the Count tried to kill Felicity via Vertigo OD. Especially considering that the Count used that very thing to escape capture from the Arrow the first time they encountered each other in the episode, hiding behind people and only giving Oliver room for kill shots, then when he did have a target, he revealed his hostage, whom Oliver chose to get out instead of going after the Count.
And afterwards, Felicity apologizes for forcing Oliver to choose between breaking his new Thou Shalt Not Killrule and letting her die. Oliver replies that as soon as her life was threatened, it wasn't a choice.
Early on, Thea is stressed out by the trial, believing she failed her mother with her testimony. Roy brings her boxing gloves and gets her to vent her anger in a weird yet cute way that proved very effective.
This one is kind of a stretch, but Malcolm saying he was overjoyed to find out that Thea is his daughter. He seems like he actually means it and wants to make amends for getting his son killed as well as be in his daughter's life.
Barry and Felicity's interactions; these two just radiate Adorkable moments. Whether it's awkward flirting or the two of them nerding out, it's definitely something sweet to see.
After confronting Barry for lying to them, Felicity is upset at Oliver, because Barry had good reasons and they do the same thing everyday. At their Q.C. party, he asks her if she has time for a dance. She replies that she doesn't want to dance with him. Oliver says he knows — and that's why he invited Barry. He made peace with him especially for Felicity. But they will card him at the bar.
Felicity bandaging Oliver up, and Oliver's scream of pain. She is taping injuries on him and he actually yells, "Ow." Oliver of a year ago would not show any weakness, signs of pain or injury to anybody. More often that not, he would be The Stoic about it all, i.e. after almost dying from a gunshot wound, his heart stopping, and the fact that he had been shocked with a defibrillator his reaction was basically, "I'm not dead, cool beans". That scene shows how far he has come from when he was on the island. The fact that he hadn't braced himself for the pain and let out a reaction with Diggle and Felicity watching shows just how far he's come in trusting them, and the bond that they share. Instead of working for Oliver Queen as Arrow, they now work with Oliver Queen as equals. Oliver, though not completely open, is showing more genuine emotions and reactions, instead of closing himself off to those around him or faking emotions he doesn't have, but should. Especially with Diggle, Felicity and Thea.
Tommy appearing as a hallucination to Oliver, saying that he was wrong to call Oliver a murderer and urging him to get up and fight back. It gives Oliver the resolve he needs to do just that and defeat Cyrus Gold, and after the saddening hallucination of Shado and the harsh, cruel one of Slade, it's all the more touching.
Quentin telling Laurel You Are Better Than You Think You Are and to stop trying to find something wrong with Sebastian because he likes her. While Laurel is right to investigate Blood, it's still a sweet moment between the two.
Moira congratulating Thea on her work at Verdant since taking over in Oliver's place.
Ollie apologizing to Felicity, and going one better:
Ollie: You're not my employee. You're my partner.
At the end of the episode, after Laurel has been disbarred and Officer Daily has died to cover for Brother Blood, the Arrow meets with Roy, who initially takes a couple of swipes at him, then admits that given the Mirakuru running through his veins, maybe the vigilante should just kill him. But Oliver isn't having it — he urges Roy to let him be a true mentor, teach him to control his anger and his new abilities. Roy's response? "When do we start?"
A quick but sweet moment, Felicity taking her own initiative in hacking Starling City's lax prison system and standing up for her actions, quickly followed by Oliver's acknowledgement of her awesomeness; the look on her face after he does so just sells it.
Oliver: You hacked into a prison system network?
Felicity: Is that judgment I'm hearing?
Oliver's continuous growth in this episode. Not only does he try to use what he's learned about Mirakuru on the island to help Roy, he acknowledges that yes, it happened and it's horrible, but maybe he can use all of that trauma in a positive, non-violent way. In addition, instead of just glossing over what he needs to do, he explains why he's doing it and talks about his experience on the island without being prodded. When he takes a risk by revealing himself to Roy, he acknowledges that he wasn't thinking about the consequences and holds himself accountable to both Diggle and Felicity by giving them the reasons for his actions instead of just ignoring their concerns.
Roy Harper: How many people know what...who you are? Oliver: Too many. But these are the only two that matter — John Diggle and Felicity Smoak.
Thea reassuring her mother that she's one of many people in Starling City beginning to see her as more than the woman they can focus their anger on for the earthquake that killed 503 people.
After almost one year of looking for the Arrow and trying to actively help him, Roy finally gets his wish and can thank him face-to-face, without a hood between them.
"Heir to the Demon":
Not only does Oliver notice something is wrong with Felicity, but when she hesitates to tell him what she's learned about Thea's true parentage, he reassures her:
Oliver: You're not going to lose me.
When Quentin and Oliver each learn about Sara's relationship with Nyssa, both assure her that this doesn't change anything with them; they still love her.
Laurel gets a few — the first is when she agrees to have a family dinner with Sara (who she recently yelled at and threw out of her house) for the sake of her father and his hopes of rekindling something with her mother. The second is when she finally, tearfully reconciles with Sara at the end of the episode. The last is when she shows up at an AA meeting that her father is attending, and the two share a tender look.
Quentin apologizing to Oliver over the way he treated him after his return, acknowledging that Ollie's not a killer.
Sin's hug upon seeing Sara for the first time since she had to leave Starling City.
The Reveal that Sara is protecting Sin because of a promise she made to her father while he was dying.
Team Arrow's efforts to remind Felicity of her value to them, especially Oliver telling Felicity that she will always be his girl. Whether or not it's romantic, it's clear that Oliver cares for Felicity very much.
Felicity's self-deprecating attempt to get in on the others' scar comparison game, to which Sara says "You're still cute."
When Felicity is at her lowest due to the Clock King burning out her network system, Diggle is the one who stays behind to give her some words of encouragement (not that Oliver didn't offer to do the same).
Diggle: I know we haven't talked about this, but it must be difficult seeing them together.
Felicity: This isn't about them being together. This is about me, okay? Sara can analyze blood, she can kick ass, she can do anything. And the one good thing I'm good at, I'm failing at miserably. And why do you need me now that you have her?
Diggle: Because you're irreplaceable, Felicity.
Oliver's talk with Felicity at the end, especially since he mentions that Diggle said (off-screen) that Felicity was feeling a little out.
Felicity: I was just...used to being your girl. I mean, not your girl-girl. Your girl. I know it sounds like the same word, but it means something different in my head.
Oliver: (cups her cheek, which she leans into) Hey. You will always be my girl, Felicity.
This line in the flashback. Later events in the episode make it a Tear Jerker, though.
Slade: When we first tried to get off this island, it was as strangers. Now it's as brothers.
This line in the present day. Just three words from a certain I.T. girl as her friends head into battle:
Felicity: Please save Oliver!
The scene with Felicity bringing Dig hot chocolate from her house.
Sara not letting Ollie pushing her away; Laurel, who doesn't even know about the threat on their heads, agrees and says they deserve to be happy.
John and Lyla saving Deadshot from the drone. Dig has come a long way from his need for revenge against his brother's killer. Knowing about Lawton's daughter didn't hurt, either.
Deadshot's entire motivation for working is to pay for anything his daughter might need, which both humanizes him greatly and is kinda sweet. Then, there's Diggle repeatedly encouraging him to try and be a real father for her instead of just sending money her way. Its pretty sweet to see how much compassion Diggle has for other people that he'd have this kind of empathy for a man he hated so badly a year before.
"Birds of Prey":
Sara and Laurel have obviously reconnected as sisters. Sara's concern and Laurel not brushing her off, but acknowledging it while pointing out she has a job to do, is a very well done scene.
Diggle putting a hand on Roy's shoulder after Roy breaks up with Thea to protect her.
Isabel Rochev handling affairs on Ollie's behalf at Queen Consolidated, and Ollie not hesitating to put his trust in her by naming her acting CEO while he finds Thea. It comes back to bite him, unfortunately, when she abuses the privilege to kick him out of his job.
Oliver and his mother (at least temporarily) reconciling.
After Oliver has fallen into practically every trap Slade set for him, he goes back down to the cave to find Felicity and Diggle, there to yank him back from the Despair Event Horizon and remind him that, even if everything else has gone wrong, they are still here for him.
"The Man under the Hood"
Quentin explaining to Laurel why he ended up not trying to discover the Arrow's identity after Laurel offered to tell him, namely because he wants the Arrow to keep his effectiveness as a symbol, instead of being a person with people he cares about and normal problems.
A villainous one when Slade injects Isabel with his blood to save her life, visibly worrying about her.
Laurel deciding not to confront Ollie and Sara with her knowledge of their identities and offering emotional support to Oliver.
The reveal that Robert knew Thea was Malcolm's daughter but this never changed a thing to him; he loved her regardless, so much so it made him stop cheating on Moira and stay with his family.
After a combination of a poor excuse behind a broken leg and admitting he had sacrificed many things in order to do good and to keep his family safe puts the pieces together for her, Moira reveals to Oliver that she had suspected he was the Arrow since the Undertaking and that she couldn't be any prouder of him.
A doctor finally getting to pay back the Arrow for stopping the Triad from stealing medicine months ago after Roy damages Ollie's knee.
"City of Blood":
Felicity shows how much she believes in Oliver even as he thinks he should turn himself over to Slade:
Felicity: You can't just accept things, Oliver. If I had accepted my life, I would be a cocktail waitress in Vegas like my mother, and I never would have gone to college. I never would have moved a thousand miles away to work at Queen Consolidated, and I never would have believed some crazy guy in a hood when he told me I could be more than just some IT girl. (beat)Please don't do this.
When Oliver finally decides to surrender to Slade, either Felicity or Diggle drugs him and drags him back to the Foundry to talk some sense into him.
Oliver telling Thea he's glad to have her as a sister, and that of all their family, she was the best. And he encourages her to go wherever she wants, after which she promises to get in touch once she's settled down there.
"Streets of Fire"
Laurel telling Sara she doesn't think she's irredeemable:
Felicity's seemingly unshakable confidence that Oliver can win out over Slade.
Felicity: You honor the dead by fighting. And you are not done fighting! Malcolm Merlyn, The Count, The Clock King, The Triad, everyone who has tried to hurt this city — you stopped them. And you will stop Slade.
Oliver: I don't know how.
Felicity: Neither do I, but I do know two things: You Are Not Alone. And I believe in you.
Followed by Felicity wrapping Oliver in a tight hug and, after a moment, him relaxing into it and hugging her back.
After Sara has been beating herself up, thinking she can never be a hero after her time in the League of Assassins, she hears someone who witnessed her saving a girl from a fire calling her just that.
Then there's her doing a Stealth Hi/Bye after saving said girl, making the girl's mother ask who she was.
Laurel: That's the Canary.
There's also Oliver's initial guilt at having to test the cure on Roy, and apologizing before doing so; he's done so much wrong by Roy that he really doesn't want to do more horrible things to him.
Oliver and Anatoli's It Has Been an Honor goodbye was also rather sweet; we already know that the two will remain friends for some time given their post-island interactions, so it's nice to know that at least one person other than Sara will stay a good friend of Oliver's.
Oliver telling Roy, "Someone — a friend — once told me that if you survive a crucible, you grow the stronger for it." Who said that to Oliver? Sebastian Blood.
There's also the fact he had a mask made already for Roy to use, showing it wasn't a spontaneous decision to take him out into the field; he's been planning for a while to let Roy join him properly, just as he wanted.
Sara's farewell to Laurel and Quentin before leaving Starling City with Nyssa; she actually comes off as happy rather than resigned. On the same note, Nyssa promising Quentin that she will protect Sara with her own life.
It's a blink-and-you'll-miss-it moment and is hard to see, but before Sara goes to her father and sister, Nyssa has her around Sara's waist.
Felicity and Oliver's talk on the beach of Lian Yu, after all the dust has settled; she's trying in her usual adorkable way to cover up for him saying "I love you" as part of their plan to outmaneuver Slade, and he's just smiling at her with the sunlight on his face, and when she finishes with "You really sold it", he simply replies, "We both did." Ship Tease or no, it's a testament to how much she believes in him that she went along with the plan, and how much he obviously trusts her to be able to handle such a dangerous situation.
Both the videos John Barrowman uploaded of the cast hanging out (as seen in the Funny page), especially since the actors involved (Barrowman and Colton Haynes) never interact on screen.
Stephen Amell, David Ramsey, and Emily Bett Rickards recording a video as part of the "Batkid" Make-A-Wish project (a heartwarming story in it's own right). Add to that the fact that, unlike other videos from the set which are little more than Stephen Amell goofing around with his smartphone, this was a professionally done scene, meaning that at least part of the crew also volunteered their time to record it.